Formation of Linear Supramolecular Polymers That Is Driven by C-H···π Interactions in Solution and in the Solid State

摘要

C—H···π interactions are the weakest hydrogen bonds (1.5-2.5 kcalmol~(-1)), and they occur between soft acids and soft bases. They are weaker than the classical hydrogen bonds between NH/O, NH/N, O/OH, and N/OH groups (3-7 kcal mol~(-1)). However, they have played significant roles in various fields of chemistry and biological systems, for example in determining the conformations of molecules, crystal packing,host-guest chemistry reaction selectivity, and the self-assembly of molecules into organized supramolecular structures. Their importance in the stabilization of conformations and structures of proteins and DNA has also been suggested in recent years. On the other hand, supramolecular polymers, assembled from low molecular weight monomeric units by specific directional secondary interactions, such as hydrogen bonds, π-π interactions, hydrophobic interactions, and metal-ligand bonds, have demonstrated traditional polymeric properties and become an important part of stimuli-responsive dynamic materials. Although C—H···π interactions have been used in construction of discrete supramolecular architectures, supramolecular polymers driven by the C—H···π interactions have not been reported to date. Up to now, many small molecules have been used to prepare supramolecular polymers, but their preparation usually requires multiple steps and is time-consuming. To find a simple way to make monomers for the preparation of supramolecular polymers is very important for future applications of supramolecular polymers. However, this still is a challenging mission for chemists.